The obiective of the Physiology Core is to be a resource for DERC members to facilitate diabetes-related research dealing with biological outcomes in normal and diabetic rodents (rats and mice) as well as in genetically engineered rodents. These activities may require any or all of the following: a) placement of catheters or probes for infusion and sampling (rats and mice), b) isolation of islets (rats and mice), c) help in the performance of glucose clamps or tolerance tests (rats only), and d) measurements of glucoregulatory hormones (rats and mice). The Physiology Core provides the centralized facilities, services and expertise to efficiently accomplish these tasks. It is divided into two Sub-cores, i.e., Animal Surgery and Hormone Assay. The aims of the Animal Surgery Sub-core are two-fold: 1) to provide DERC investigators with laboratory facilities and expertise to conduct diabetes-related, in vivo physiological experiments in awake non-diabetic or diabetic rodents, and 2) to be a resource for DERC members to facilitate islet-related research by providing freshly isolated rodent pancreatic islets, insulinoma lines as well as pancreatic lymph node cells. A centralized facility to conduct surgery for chronic catheter placement to carry out difficult metabolic studies in rodents and to efficiently generate islets is very useful for diabetes research, but is not easily accessible to investigators without previous training or experience. The Sub-Core will provide expertise, services and education, thereby giving DERC members access to the specialized experimental methodologies and the equipment necessary to apply them to diabetes. Moreover, it is anticipated that the Sub-core will provide a vehicle for collaboration between members with basic science research, and members whose focus is clinical physiology and metabolism. The Hormone Assay Sub-core provides DERC members with centralized facilities for measurements of glucoregulatory hormones and neurotransmitters that are derived from animal studies. This component of the Physiology Core takes advantage of the Yale GCRC Core Laboratory that is used for clinical studies. The Subcore benefits from the technical expertise and equipment of an ongoing and productive radioimmunoassay and HPLC facility, thereby allowing us to maximize quality and minimize the cost of operation. As a result, DERC members have access to a centralized facility that makes available personnel, methodology, instrumentation, and quality control required to efficiently perform hormone assays relevant to diabetes.